Multi-band directional scanning

ABSTRACT

Examples described herein provide multi-band directional scanning. Examples may include receiving, by a first radio of a first network device operating at a first frequency band below the millimeter-wave (mmWave), a probe request from a second network device indicating a protocol and a particular sector receiving direction of the second network device, and in response to the protocol indicated by the probe request, transmitting, by a second radio of the first network device operating at a second frequency band within the mmWave, a probe response in each of one or more sector transmitting directions, wherein the second network device receives one or more probe responses in the particular sector receiving direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of PCT Application No.PCT/CN2019/084070, filed on Apr. 24, 2019, which is hereby incorporatedherein by reference in its entirety. This application is also related toU.S. application Ser. No. 17/599,706, filed on Sep. 29, 2021, whichclaims the benefit of PCT Application No. PCT/CN2019/084078, filed onApr. 24, 2019, which has Invention Reference Number 90731248 and isassigned to Hewlett Packard Enterprise Development LP, which is herebyincorporated herein by reference in its entirety.

BACKGROUND

In recent years, millimeter-wave (mmWave) network devices have attracteda great deal of attention from industry. As used herein, the term“mmWave” refers to the radio frequency (RF) spectrum between 10 GHz and300 GHz. A mmWave network device may transmit and/or receive signals atmmWave bands to establish wireless communication links between nodes ofa network.

MmWave bands may provide at least the following advantages overfrequency bands below 10 GHz. First, mmWave bands may offer widerchannel bandwidths as compared to frequency bands below 10 GHz. Forinstance, whereas the IEEE 802.11ad standard for the 60 GHz bandprovides channel bandwidths of 2.16 GHz, the IEEE 802.11 ac standard forthe 5 GHz band only provides channel bandwidths of up to 160 MHz.Second, whereas channels for frequency bands below 10 GHz (e.g., 2.4GHz, 5 GHz) are becoming increasingly congested by Fourth GenerationLong Term Evolution (4G LTE) and Wi-Fi networks, some mmWave bands areunlicensed and freely available for use. For instance, in somejurisdictions, the 60 GHz band offers 7 GHz of continuous, unlicensedspectrum.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features and advantages of the invention will become apparentfrom the following description of examples of the invention, given byway of example only, which is made with reference to the accompanyingdrawings, of which:

FIG. 1 is a block diagram of an example network device for multi-banddirectional scanning.

FIG. 2 is a block diagram of an example system including first networkdevice and second network device for multi-band directional scanning.

FIG. 3 is a block diagram of an example system including first networkdevice and second network device for multi-band directional scanning.

FIGS. 4A and 4B show a flowchart of an example process for multi-banddirectional scanning.

FIG. 5 is a block diagram of an example computer system in which variousembodiments described herein of multi-band directional scanning may beimplemented.

DETAILED DESCRIPTION

As noted above, mmWave network devices may transmit and/or receivemmWave signals to establish wireless communication links between nodesof a network. In some examples, mmWave network devices may providebackhaul connectivity between networks. In examples described herein, a“backhaul” refers to communication links between nodes of one or morenetworks and a backbone network (i.e., core network). In such examples,a first mmWave network device may operate as a root node (i.e., gatewaynode) which is connected to a backbone network via a wired and/orwireless communication link, and a second mmWave network device mayoperate as a remote node which is connected to the first mmWave networkdevice via a wireless communication link. In such examples, the firstand second mmWave network devices may establish wireless communicationlinks with other nodes of one or more networks to provide backhaulconnectivity to the backbone network.

It may be advantageous to use mmWave network devices to provide backhaulconnectivity between networks, for at least the following reasons.First, as noted above, since mmWave signals may provide increasedbandwidths as compared to signals below 10 GHz, mmWave network devicesmay offer greater throughput as compared to network devices which canonly operate at frequency bands below 10 GHz. Second, as noted above,since some mmWave bands are unlicensed and freely available to use,using mmWave network devices to provide backhaul connectivity betweennetworks may be less expensive as compared to using leased lines orwireless connections at licensed frequency bands below 10 GHz.

Despite the great potential that mmWave network devices offer forproviding backhaul connectivity between networks, mmWave signals may bemore susceptible to propagation loss than signals below 10 GHz. Forinstance, because mmWave signals have shorter wavelengths (i.e., higherfrequency) as compared to signals below 10 GHz, mmWave signals mayexperience greater propagation loss due to line-of-sight (LOS)obstructions, atmospheric attenuation, and weather conditions (e.g.,humidity, rain, etc.) To mitigate the effects of propagation loss,mmWave network devices may increase gain by transmitting and receivingdirectional mmWave signals having narrower beamwidths. However, asexplained herein, passive directional scanning requires a first mmWavenetwork device to transmit, via a frequency band within the mmWaverange, a beacon frame for each available sector scanning direction of asecond mmWave network device to establish a wireless communication linkbetween the first and second mmWave network devices. As explainedherein, such passive directional scanning may result in long scan timeswhen there are a plurality of available sector transmitting and sectorscanning directions between the first and second mmWave network devices.

To address these issues, examples described herein may receive, by afirst radio of a first network device operating at a first frequencyband below the mmWave, a probe request from a second network deviceindicating a protocol and a particular sector scanning direction of thesecond network device. Examples described herein may, in response to theprotocol indicated by the probe request, transmit, by a second radio ofthe first network device operating at a second frequency band within themmWave, a probe response in each of one or more sector transmittingdirections, wherein the second network device receives one or more proberesponses in the particular sector scanning direction.

In this manner, examples described herein may provide multi-banddirectional scanning between network devices. For instance, in suchexamples, the first network device may receive the probe requestindicating the sector scanning direction of the second network devicevia the first frequency band below the mmWave, thereby avoidingrequiring the first network device to send, via a frequency band withinthe mmWave, a beacon frame for every sector scanning direction of thesecond network device. In addition, in such examples, the first networkdevice may, in response to the protocol indicated by the probe request,transmit the probe response in each of one or more sector transmittingdirections via the second frequency band within the mmWave, therebyallowing one or more probe responses to be received by the secondnetwork device in the particular sector scanning direction, rather thanrequiring probe responses to be received by the second network device inevery sector scanning direction. Thus, examples described may providemay reduce scan times for establishing wireless communication linksbetween network devices.

Referring now to the drawings, FIG. 1 is a block diagram of an examplenetwork device 100 for multi-band directional scanning. In the exampleof FIG. 1 , network device 100 (which may be referred to herein as“first” network device 100) includes at least one processing resource110 and at least one machine-readable medium 120 comprising (e.g.,encoded with) at least instructions 122 that are executable by the atleast one processing resource 110 of network device 100 to implementfunctionalities described herein in relation to instructions 122.

In the example of FIG. 1 , network device 100 may engage in any networkdata transmission operations, including, but not limited to, switching,routing, bridging, or a combination thereof. In some examples, networkdevice 100 may comprise a wireless access point (WAP). In examplesdescribed herein, a “WAP” generally refers to receiving points for anyknown or convenient wireless access technology which may later becomeknown. Specifically, the term WAP is not intended to be limited to WAPswhich conform to IEEE 802.11 standards. A WAP generally functions as anelectronic device that is adapted to allow wireless devices to connectto a wired network via various communications standards. A WAP mayinclude any necessary hardware components to perform the inventionsdisclosed herein, including, but not limited to: processors, memories,display devices, input devices, communications equipment, etc. It willbe understood by one of ordinary skill in the art that network device100 may be any suitable type(s) of network devices made by any suitablemanufacturer(s).

In the example of FIG. 1 , network device 100 includes a first radio 130and a second radio 140. In some examples, first radio 130 may operate ata first frequency band below the mmWave (i.e., a frequency band below 10GHz.) In some examples, first radio 130 may operate at a frequency bandwithin the range of 400 MHz to 7 GHz. For example, first radio 130 mayoperate at a 5 GHz band which conforms to the IEEE 802.11 ac standard, a2.4 GHz band which conforms to one or more of the IEEE 802.11ac,802.11n, and 802.11g standards, or a combination thereof. It will beunderstood by one skilled in the art that first radio 130 may transmitand receive wireless signals that conform to any suitable type(s) ofwireless communications standard(s), now known or later developed,and/or operate at any suitable frequency range(s). In some examples,first radio 130 may comprise an antenna which transmits directionaland/or omnidirectional signals. In examples described herein, a“directional” signal refers to a signal which radiates more strongly inone or more directions as compared to one or more other directions alongan azimuth plane (i.e., horizontal plane), whereas an “omnidirectional”signal refers to a signal which radiates equally in all directions alongan azimuth plane. In some examples, first radio 130 may comprise aphased array antenna. In examples described herein, a “phased arrayantenna” refers to an array of antennas which can create a directionalsignal which can be electronically steered to point in differentdirections without moving the antennas. In some examples, the phasedarray antenna may comprise an array of directional and/oromnidirectional antennas which can focus RF energy towards specificspatial directions.

In the example of FIG. 1 , second radio 140 may operate at a secondfrequency band within the mmWave. In some examples, second radio 140 mayoperate at a frequency band within the range of 24 to 300 GHz. Forexample, second radio 140 may operate at a 60 GHz band which conforms toone or both of the IEEE 802.11ad and 802.11ay standards. It will beunderstood by one skilled in the art that second radio 140 may transmitand receive wireless signals that conform to any suitable type(s) ofwireless communications standard(s), now known or later developed,and/or operate at any suitable frequency range(s). In some examples,second radio 140 may comprise an antenna which transmits and receivesdirectional signals. In some examples, second radio 140 may comprise aphased array antenna. In some examples, second radio 140 may transmitand receive directional signals in one or more of a plurality of sectordirections 150_1 to 150_n (collectively referred to as sector directions150), wherein n is an integer greater than one. For example, secondradio 140 may transmit and receive directional signals in 32 sectordirections (i.e., 150_1 to 150_32.) In some examples, each one of sectordirections 150 may correspond to a plurality of beam directions. Forexample, as shown in FIG. 1 , each one of sector directions 150 maycorrespond to four beam directions. It will be understood by one skilledin the art that second radio 140 may provide any suitable number(s) ofsector directions 150 and beam directions. Moreover, although FIG. 1shows that network device 100 comprises two radios, it will beunderstood by one skilled in the art that network device 100 maycomprise four, eight, or any suitable number of radios.

In the example of FIG. 1 , first radio 130 may establish a wirelesscommunication link 160 with a second network device, and second radio140 may establish a wireless communication link 170 with the secondnetwork device. In some examples, wireless communication links 160 and170 may use any suitable data transmission protocol(s), including atleast one connection-oriented protocol such as Transmission ControlProtocol (TCP), at least one connectionless protocol such as UserDatagram Protocol (UDP), or the like, or a combination thereof. It willbe understood by one skilled in the art that each of wirelesscommunication links 160 and 170 may use any suitable type(s) of datatransmission protocol(s), now known or later developed.

In the example of FIG. 1 , instructions 122 may be configured toreceive, by first radio 130, a probe request 162 from a second networkdevice indicating a protocol and particular sector scanning direction ofa second network device. In some examples, probe request 162 maycomprise an Ethernet frame having a frame format which conforms to theIEEE 802.3 standards. In some examples, probe request 162 may comprise adata packet comprising a header and a payload. In examples describedherein, a header may comprise control information for delivering thepayload, such as source and destination information, sequencinginformation, service information, flagging information, othertransmission-related information, or the like, or a combination thereof.In examples described herein, a payload may comprise data which iscarried by the data packet. In some examples, probe request 162 maycomprise a field indicating the specific protocol. In some examples, thespecific protocol may instruct first network device 100 to transmit aprobe response via second radio 140. In some examples, probe request 162may comprise a field comprising a value indicating the particular sectorscanning direction of a second network device. In some examples, proberequest 162 may indicate a particular scanning channel of the secondfrequency band. In some examples, probe request 162 may indicate aparticular scanning duration of the second network device. In someexamples, probe request 162 may indicate a particular sectortransmitting direction of network device 100. It will be understood byone skilled in the art that probe request 162 may have any suitableformat(s) and any suitable type(s) of field(s), now known or laterdeveloped.

In the example of FIG. 1 , instructions 122 may be configured to, basedon (e.g., in response to) the protocol indicated by probe request 162,transmit, by second radio 140, a probe response 172 in each of one ormore sector transmitting directions, wherein the second network devicereceives one or more probe responses 172 in the particular sectorscanning direction. In some examples, one or more sector transmittingdirections may correspond to sector directions 150_1 to 150_n. Forexample, when n is equal to 32, instructions 122 may be configured totransmit, by second radio 140, probe response 172 in each of 32 sectordirections (i.e., 150_1 to 150_32.) In some examples, probe response 172may comprise a management frame having a frame format which conforms tothe IEEE 802.11 standards. In some examples, probe response 172 maycomprise a data packet comprising a header and a payload. In someexamples, probe response 172 may indicate one or more Basic Service SetIdentifiers (BSSIDs), one or more Service Set Identifiers (SSIDs), oneor more Extended Service Set Identifiers (ESSIDs), or a combinationthereof. It will be understood by one skilled in the art that proberesponse 172 may have any suitable format(s) and any suitable type(s) offield(s), now known or later developed.

In the example of FIG. 1 , instructions 122 may be configured toreceive, by second radio 140, an authentication request from the secondnetwork device, wherein the authentication request is based on (e.g., inresponse to) one or more probe responses 172 received by the secondnetwork device in the particular sector scanning direction. In theexample of FIG. 1 , instructions 122 may be configured to, based on(e.g., in response to) the authentication request, transmit, by secondradio 140, an authentication response to the second network device. Insome examples, instructions 122 may be configured to receive theauthentication request and/or transmit the authentication response in aparticular sector direction corresponding to a particular one of sectordirections 150. In some examples, instructions 122 may be configured toreceive the authentication request and/or transmit the authenticationresponse in a particular sector direction corresponding to a particularsector transmitting direction indicated by probe request 162. In someexamples, instructions 122 may be configured to receive theauthentication request and/or transmit the authentication response in aparticular beam direction corresponding to a particular one of sectordirections 150. In some examples, the authentication request maycomprise a field indicating an authentication algorithm number. In someexamples, the authentication algorithm number may indicate anopen-system authentication or a shared-key authentication. In someexamples, instructions 122 may be configured to transmit theauthentication response based on (e.g., in response to) an open-systemauthentication or a shared-key authentication of the authenticationrequest. In some examples, each of the authentication request and theauthentication response may comprise a management frame having a frameformat which conforms to the IEEE 802.11 standards. In some examples,each of the authentication request and the authentication response maycomprise a data packet comprising a header and a payload. It will beunderstood by one skilled in the art that each of the authenticationrequest and the authentication response may have any suitable format(s)and any suitable type(s) of field(s), now known or later developed.

In the example of FIG. 1 , instructions 122 may be configured toreceive, by second radio 140, an association request from the secondnetwork device, wherein the association request is based on (e.g., inresponse to) one or more probe responses 172 received by the secondnetwork device in the particular sector scanning direction. In theexample of FIG. 1 , instructions 122 may be configured to, based on(e.g., in response to) the association request, transmit, by secondradio 140, an association response to the second network device toestablish a connection with the second network device. In some examples,instructions 122 may be configured to receive the association requestand/or transmit the association response in a particular sectordirection corresponding to a particular one of sector directions 150. Insome examples, instructions 122 may be configured to receive theassociation request and/or transmit the association response in aparticular sector direction corresponding to a particular sectortransmitting direction indicated by probe request 162. In some examples,instructions 122 may be configured to receive the association requestand/or transmit the association response in a particular beam directioncorresponding to a particular one of sector directions 150. In someexamples, each of the association request and the association responsemay comprise a management frame having a frame format which conforms tothe IEEE 802.11 standards. In some examples, each of the associationrequest and the association response may comprise a data packetcomprising a header and a payload. It will be understood by one skilledin the art that each of the association request and the associationresponse may have any suitable format(s) and any suitable type(s) offield(s), now known or later developed.

In the example of FIG. 1 , instructions 122 may be configured to, basedon (e.g., in response to) an established connection with the secondnetwork device, transmit, by second radio 140, a data frame to thesecond network device. In the example of FIG. 1 , instructions 122 maybe configured to, based on (e.g., in response to) an establishedconnection with the second network device, receive, by the second radio,a data frame from the second network device. In some examples,instructions 122 may be configured to transmit and/or receive a dataframe in a particular sector direction corresponding to a particular oneof sector directions 150. In some examples, instructions 122 may beconfigured to transmit and/or receive a data frame in a particularsector direction corresponding to the particular sector transmittingdirection indicated by probe request 162. In some examples, instructions122 may be configured to transmit and/receive a data frame in aparticular beam direction corresponding to a particular one of sectordirections 150. In some examples, a data frame may comprise a frameformat which conforms to the IEEE 802.11 standards. It will beunderstood by one skilled in the art that the data frame may have anysuitable format(s) and any suitable type(s) of field(s), now known orlater developed.

Next, a duration of multi-band directional scanning according to thepresent invention will be explained in relation to the example of FIG. 1. In the example of FIG. 1 , a duration of multi-band directionalscanning may be equal to (time of probe request 162+time of proberesponse 172)×(number of sector transmitting directions). Moreover, theduration of multi-band directional scanning may include time forre-transmission of probe request 162 and/or probe response 172 due tochannel contention. For example, provided that (time of probe request162|probe response 172|time for re-transmission) is approximately 2 ms,when network device 100 has 32 sector transmitting directions, theduration of multi-band directional scanning may be approximately equalto 2 ms×(32 sector transmitting directions), or approximately 64 ms.Moreover, in such example, when the second network device has 32 sectorscanning directions, the duration of multi-band directional scanning foreach available sector scanning direction of the second network devicemay be approximately equal to 64 ms×(32 sector scanning directions), orapproximately 2 seconds. Moreover, in such example, provided that secondradio 140 has three available channels corresponding to the secondfrequency band within the mmWave, the duration of multi-band directionalscanning for all three channels may be approximately equal to 2seconds×(3 channels for the second frequency band), or approximately sixseconds.

For comparison, a duration of passive directional scanning (i.e.,directional scanning without performing the method of the inventiondescribed herein) will be described in relation to the example of FIG. 1. In the example of FIG. 1 , passive directional scanning requiresnetwork device 100 to transmit, via second radio 140 operating at thesecond frequency band within the mmWave, a beacon frame for each of aplurality of sector scanning directions of the second network device ineach of the plurality of sector directions 150. Thus, the duration ofpassive directional scanning may be equal to (beacon interval of thebeacon frame)×(number of sector transmitting directions)×(number ofsector scanning directions). For example, provided that the beaconinterval is approximately 100 ms, when network device 100 has 32 sectortransmitting directions, and when the second network device has 32available sector scanning directions, the duration of passivedirectional scanning for a given channel within the second frequencyband may be approximately equal to 100 ms×(32 sector scanningdirections)×(32 sector transmitting directions), or approximately 102.4seconds. Moreover, in such example, provided that second radio 140 hasthree available channels corresponding to the second frequency band, theduration of passive directional scanning for all three channels for thesecond frequency band may be approximately equal to 102.4 seconds×(3channels for the second frequency band), or approximately five minutes.

In this manner, the example network device 100 of FIG. 1 may providemulti-band directional scanning. For instance, instructions 122 may beconfigured to receive, by first radio 130 operating at the firstfrequency band below the mmWave, probe request 162 from the secondnetwork device indicating the protocol and the particular sectorscanning direction of the second network device, thereby avoidingrequiring network device 100 to send, via the second frequency bandwithin the mmWave, a beacon frame for every sector scanning direction ofthe second network device. Moreover, instructions 122 may be configuredto, in response to the protocol indicated by probe request 162,transmit, by second radio 140 operating at the second frequency bandwithin the mmWave, probe response 172 in each of one or more sectordirections 150, wherein the second network device receives one or moreprobe responses 172 in the particular sector scanning direction, therebyallowing one or more probe responses 172 to be received by the secondnetwork device in the particular sector scanning direction, rather thanrequiring one or more probe responses 172 to be received in every sectorscanning direction of the second network device. Thus, examplesdescribed herein may provide may reduce scan times for establishingwireless communication links between network devices as compared topassive directional scanning.

FIG. 2 is a block diagram of an example system 201 for multi-banddirectional scanning. In the example of FIG. 2 , system 201 may includefirst network device 100, as described above in relation to FIG. 1 .System 201 may include a second network device 200.

In the example of FIG. 2 , second network device 200 includes at leastone processing resource 210 and at least one machine-readable medium 220comprising (e.g., encoded with) at least instructions 222 that areexecutable by the at least one processing resource 210 of second networkdevice 200 to implement functionalities described herein in relation toinstructions 222. In some examples, one or more instructions 222 may bethe same as or similar to one or more instructions 122, as describedabove.

In the example of FIG. 2 , second network device 200 may engage in anynetwork data transmission operations, including, but not limited to,switching, routing, bridging, or a combination thereof. In someexamples, second network device 200 may comprise a WAP. It will beunderstood by one of ordinary skill in the art that second networkdevice 200 may be any suitable type(s) of network devices made by anysuitable manufacturer(s).

In the example of FIG. 2 , second network device 200 includes a firstradio 230 and a second radio 240. In some examples, first radio 230 mayoperate at the same frequency band as first radio 130 of first networkdevice 100. In some examples, first radio 230 may operate at a firstfrequency band below the mmWave (i.e., a frequency band below 10 GHz.)In some examples, first radio 230 may operate at a frequency band withinthe range of 400 MHz to 7 GHz. For example, first radio 230 may operateat a 5 GHz band which conforms to the IEEE 802.11ac standard, a 2.4 GHzband which conforms to one or more of the IEEE 802.11ac, 802.11n, and802.11g standards, or a combination thereof. It will be understood byone skilled in the art that first radio 230 may transmit and receivewireless signals that conform to any suitable type(s) of wirelesscommunications standard(s), now known or later developed, and/or operateat any suitable frequency range(s). In some examples, first radio 230may comprise an antenna which transmits directional and/oromnidirectional signals. In some examples, first radio 230 may comprisea phased array antenna.

In the example of FIG. 2 , second radio 240 may operate at a secondfrequency band within the mmWave. In some examples, second radio 240 mayoperate at the same frequency band as second radio 140 of first networkdevice 100. In some examples, second radio 240 may operate at afrequency band within the range of 24 to 300 GHz. For example, secondradio 140 may operate at a 60 GHz band which conforms to one or both ofthe IEEE 802.11ad and 802.11 ay standards. It will be understood by oneskilled in the art that second radio 240 may transmit and receivewireless signals that conform to any suitable type(s) of wirelesscommunications standard(s), now known or later developed, and/or operateat any suitable frequency range(s). In some examples, second radio 240may comprise an antenna which transmits and receives directionalsignals. In some examples, second radio 240 may comprise a phased arrayantenna. In some examples, second radio 240 may transmit and receivedirectional signals in one or more of a plurality of sector directions250_1 to 250_m (collectively referred to as sector directions 250),wherein m is an integer greater than one. In some examples, the number mof sector directions 250 may be the same as the number n of sectordirections 150 of second radio 140 of first network device 100. Forexample, second radio 240 may transmit and receive directional signalsin 32 sector directions (i.e., 250_1 to 250_32.) In some examples, eachof the sector directions 250 may correspond to a plurality of beamdirections. In some examples, each of sector directions 250 may eachhave the same number of beam directions as sector directions 150 ofsecond radio 140 of first network device 100. For example, as shown inFIG. 2 , each of the sector directions 250 may correspond to four beamdirections. It will be understood by one skilled in the art that secondradio 240 may provide any suitable number(s) of sector directions 250and beam directions. Moreover, although FIG. 2 shows that second networkdevice 200 comprises two radios, it will be understood by one skilled inthe art that second network device 200 may comprise, four, eight, or anysuitable number of radios, and that second network device 200 may have asame number or a different number of radios as first network device 100.

In the example of FIG. 2 , first radio 130 of first network device 100may establish wireless communication link 160 with first radio 230 ofsecond network device 200. In the example of FIG. 2 , second radio 140of first network device 100 may establish wireless communication link170 with second radio 240 of second network device 200.

In the example of FIG. 2 , instructions 222 may be configured totransmit, by first radio 230, probe request 162 indicating the protocoland the particular sector scanning direction. In some examples,instructions 222 may be configured to transmit probe request 162 tofirst radio 130 of first network device 100. In some examples, theparticular sector scanning direction may correspond to a particular oneof sector directions 250.

In the example of FIG. 2 , instructions 222 may be configured toreceive, by second radio 140, one or more probe responses 172 in theparticular sector scanning direction.

In the example of FIG. 2 , instructions 222 may be configured to, basedon (e.g., in response to) one or more probe responses 172 received inthe particular sector scanning direction, transmit, by second radio 240,the authentication request to first network device 100. In the exampleof FIG. 2 , instructions 222 may be configured to receive, by secondradio 240, the authentication response in a particular sector direction.In some examples, instructions 222 may be configured to transmit theauthentication request and/or receive the authentication response in aparticular sector direction corresponding to the particular one ofsector directions 250. In some examples, instructions 222 may beconfigured to transmit the authentication request and/or receive theauthentication response in the particular sector scanning directionindicated by probe request 162. In some examples, instructions 222 maybe configured to transmit the authentication request and/or receive theauthentication response in a beam direction corresponding to aparticular one of sector directions 250.

In the example of FIG. 2 , instructions 222 may be configured to, basedon (e.g., in response to) one or more probe responses 172 received inthe particular sector scanning direction, transmit, by second radio 240,the association request to first network device 100. In the example ofFIG. 2 , instructions 222 may be configured to receive, by second radio240, the association response in a particular sector direction toestablish a connection with the first network device. In some examples,instructions 222 may be configured to transmit the association requestand/or receive the association response in a particular sector directioncorresponding to the particular one of sector directions 250. In someexamples, instructions 222 may be configured to transmit the associationrequest and/or receive the association response in the particular sectorscanning direction indicated by probe request 162. In some examples,instructions 222 may be configured to transmit the association requestand/or receive the association response in a beam directioncorresponding to a particular one of sector directions 250.

In the example of FIG. 2 , instructions 222 may be configured to, basedon (e.g., in response to) an established connection with first networkdevice 100, receive, by second radio 240, a data frame from firstnetwork device 100. In the example of FIG. 2 , instructions 222 may beconfigured to, based on (e.g., in response to) an established connectionwith first network device 100, transmit, by second radio 240, a dataframe to first network device 100. In some examples, instructions 222may be configured to receive and/or transmit a data frame in aparticular sector direction corresponding to a particular one of sectordirections 250. In some examples, instructions 222 may be configured toreceive and/or transmit a data frame in a particular sector directioncorresponding to the particular sector scanning direction indicated byprobe request 162. In some examples, instructions 22 may be configuredto receive and/transmit a data frame in a particular beam directioncorresponding to a particular one of sector directions 250.

In this manner, the example system 201 of FIG. 2 may provide multi-banddirectional scanning. For instance, instructions 222 may be configuredto transmit, by first radio 230, probe request 162 indicating theprotocol and the particular sector scanning direction, thereby avoidingrequiring second network device 200 to send, via a frequency band withinthe mmWave, a beacon frame for every sector scanning direction (e.g.,sector directions 250) Moreover, instructions 222 may be configured toreceive, by second radio 140, one or more probe responses 172 in theparticular sector scanning direction, thereby allowing second networkdevice 200 to receive one or more probe responses 172 in the particularsector scanning direction, rather than requiring one or more proberesponses 172 to be received in every sector scanning direction (e.g.,sector directions 250.) Thus, examples described herein may provide mayreduce scan times as compared to passive directional scanning.

FIG. 3 is a block diagram of an example system 301 for multi-banddirectional scanning. In the example of FIG. 3 , system 301 may includefirst network device 100 and second network device 200, as describedabove in relation to FIGS. 1 and 2 . In the example of FIG. 3 , system301 may include a network 300, first client device 320, and secondclient device 340. In some examples, functionalities described herein inrelation to FIG. 3 may be provided in combination with functionalitiesdescribed herein in relation to any of FIGS. 1-2 and 4-5 .

In the example of FIG. 3 , network 300 may comprise a computer network.In some examples, network 300 may comprise one or more local areanetworks (LANs), virtual LANs (VLANs), wireless local area networks(WLANs), virtual private networks (VPNs), wide area networks (WANs), theInternet, or the like, or a combination thereof. In examples describedherein, a WAN may comprise, for example, a wired WAN, wireless WAN,hybrid WAN, software-defined WAN (SD-WAN), or the like, or a combinationthereof. In the example of FIG. 3 , network 300 may comprise a cellularnetwork. In the example of FIG. 3 , network 300 may comprise acombination of one or more computer networks and one or more cellularnetworks. In some examples, network 300 may comprise a backbone network.It will be understood by one skilled in the art that network 300 maycomprise any suitable type(s) of network(s), now known or laterdeveloped. Moreover, although FIG. 3 shows that network 300 may beconnected to first network device 100, it will be understood by oneskilled in the art that network 300 may also be connected to secondnetwork device 200.

In the example of FIG. 3 , each of first client device 320 and secondclient device 340 may comprise a processor, memory, and input/outputinterfaces for wired and/or wireless communication. In some examples,one or both of first client device 320 and second client device 340 maycomprise a laptop computer, a desktop computer, a mobile device, and/orother wireless devices, although examples of the disclosure are notlimited to such devices. In examples described herein, a mobile devicemay refer to devices that are (or may be) carried and/or worn by a user.For instance, a mobile device can be a phone (e.g., a smart phone), atablet, a personal digital assistant (PDA), smart glasses, and/or awrist-worn device (e.g., a smart watch), among other types of mobiledevices. In some examples, one or both of first client device 320 andsecond client device 340 may comprise a network device which may engagein any network data transmission operations, including, but not limitedto, switching, routing, bridging, or a combination thereof. In someexamples, one or both of first client device 320 and second clientdevice 340 may comprise a WAP. Although FIG. 3 shows that system 301comprises two client devices will be understood by one skilled in theart that system 301 may comprise any suitable number of client devices.

In the example of FIG. 3 , communication links 310, 330, and 350 allowcommunication between devices of system 310. In the example of FIG. 3 ,communication link 310 allows communication between first network device100 and network 300, communication link 330 allows communication betweenfirst network device 100 and first client device 320, and communicationlink 350 allows communication between second network device 200 andsecond client device 340. In some examples, communication link 310 maybe established via first radio 130 and/or second radio 140 of firstnetwork device 100, via first radio 230 and/or second radio 240 ofsecond network device 200, or a combination thereof. In some examples,communication link 330 may be established via first radio 130 and/orsecond radio 140 of first network device 100. In some examples,communication link 350 may be established via first radio 230 and/orsecond radio 240 of second network device 200. In some examples, each ofcommunication links 310, 330, and 350 may comprise a wired link, such asa wire, a cable, an optical fiber, or the like, or a combinationthereof, a wireless link, such as a Wi-Fi link, a cellular link, or thelike, or a combination thereof, or a combination of at least one wiredlink and at least one wireless link. It will be understood by oneskilled in the art that communication link 310 may use any suitabletype(s) of wired and/or wireless link(s), now known or later developed.In some examples, each of communication links 310, 330, and 350 anysuitable data transmission protocol(s), including at least oneconnection-oriented protocol such as TCP, at least one connectionlessprotocol such as UDP, or the like, or a combination thereof. It will beunderstood by one skilled in the art that communication links 310, 330,and 350 may use any suitable type(s) of data transmission protocol(s),now known or later developed.

In the example of FIG. 3 , first network device 100 and second networkdevice 200 may provide backhaul connectivity to network 300. Forexample, first network device 100 may operate as a root node which isconnected to network 300 via a wired communication link 310, and secondnetwork device 200 may operate as a remote node which is connected tofirst network device 100 via a wireless communication link (e.g., viaone or both communication links 160, 170). In such example, firstnetwork device 100 may establish a wireless communication link 330 withfirst client device 320, and second network device 200 may establish awireless communication link 350 with second client device 340, therebyproviding backhaul connectivity to first client device 320 and secondclient device 340 to network 300.

FIGS. 4A and 4B show functionality 400 for a network device, accordingto one example. Functionality 400 may be implemented as a method or maybe executed as one or more instructions on a machine (e.g., by at leastone processor), where the one or more instructions are included on atleast one machine-readable storage medium (e.g., a non-transitorymachine readable-storage medium.) While only ten blocks are shown infunctionality 400, functionality 400 may include other actions describedherein. Additionally, although the blocks are shown in an order, blocksdepicted in FIGS. 4A and 4B may be performed in any order and at anytime. Also, some of the blocks shown in functionality 400 may be omittedwithout departing from the spirit and scope of this disclosure.Functionality 400 may be implemented on a network device according toany of the examples herein.

As shown in block 405, functionality 400 may include receiving, by afirst radio of a first network device operating a first frequency bandbelow the mmWave, a probe request indicating a specific protocol and aparticular sector scanning direction of a second network device.

In some examples, the probe request may be received from a secondnetwork device. In addition, the probe request may be received from afirst radio of the second network device operating at the firstfrequency band below the mmWave.

In some examples, the probe request may indicate a particular channelscanning direction of the second network device. In some examples, theprobe request may indicate a particular scanning duration of the secondnetwork device. In some examples, the probe request may indicate aparticular sector transmitting direction of the first network device.

In examples described herein, the particular sector transmitting and/orreceiving direction of the first network device, as indicated by theprobe request, may be based on determining a quality of one or moresignals transmitted by the first network device in one or more sectortransmitting directions and received by the second network device.

In examples described herein, the quality of one or more signalsreceived by the second network device may be determined based onmeasuring, by the second network device, a received signal strengthindicator (RSSI) of the one or more received signals. For example, thesignal having the highest RSSI among the one or one or more receivedsignals may be determined to have the highest quality. It will beunderstood that any suitable methods(s) and/or measurement(s) may beused for determining the quality of one or more signals received by thesecond network device.

As shown in block 410, functionality 400 may include determining whetherthe probe request indicates a particular sector transmitting directionof the first network device.

If it is determined that the probe request indicates a particular sectortransmitting direction of the first network device, then functionality400 proceeds to block 420. If it is determined the probe request doesnot indicate a particular sector transmitting direction of the firstnetwork device, then functionality 400 proceeds to block 415.

As shown in block 415, functionality 400 may include transmitting, by asecond radio of the first network device operating at a second frequencyband within the mmWave, a probe response in each sector transmittingdirection of the first network device. The probe response may betransmitted based on (e.g., in response to) the probe request receivedby the first radio of the first network device. In some examples, theprobe response may be transmitted based on (e.g., in response to) thespecific protocol indicated by the probe request. In some examples, theprobe response may be transmitted to the second network device. Inaddition, the probe response may be transmitted to a second radio of thesecond network device operating at the second frequency band within themmWave.

As shown in block 420, functionality 400 may include transmitting, bythe second radio of the first network device, a probe response in theparticular sector transmitting direction. The probe response may betransmitted based on (e.g., in response to) the particular sectortransmitting direction indicated by the probe request. In some examples,the probe response may be transmitted to the second network device. Inaddition, the probe response may be transmitted to a second radio of thesecond network device.

As shown in block 425, functionality 400 may include receiving, by thesecond radio of the first network device, an authentication request. Insome examples, the authentication request may be received from thesecond network device. In addition, the authentication request may bereceived from the second radio of the second network device.

The authentication request may be received in a particular sectorreceiving direction of the first network device. The particular sectorreceiving direction of the first network device may correspond to aparticular sector transmitting direction of the first network device. Inaddition, the sector transmitting direction of the first network devicemay correspond to the particular sector transmitting direction indicatedby the probe response. In some examples, the authentication request maybe received in a particular beam receiving direction of the firstnetwork device corresponding to the sector transmitting direction.

In examples described herein, the particular sector transmitting and/orreceiving direction of the first network device, as indicated by theprobe response, may be based on determining a quality of one or moresignals transmitted by the first network device in one or more sectortransmitting directions and received by the second network device in theparticular sector scanning direction.

As shown in block 430, functionality 400 may include transmitting, bythe second radio of the first network device, an authentication responsein a particular sector transmitting direction. The authenticationresponse may transmitted based on (e.g., in response to) authenticatingthe authentication request. In some examples, the authentication requestmay be authenticated based on open-system authentication or shared-keyauthentication.

In some examples, the authentication response may be transmitted to thesecond network device. In addition, the authentication response may betransmitted to the second radio of the second network device. Theauthentication response may be transmitted in a sector transmittingdirection corresponding to a particular sector transmitting directionindicated by the probe request. In some examples, the authenticationresponse may be transmitted in a particular beam transmitting directioncorresponding to a particular sector transmitting direction of the firstnetwork device.

As shown in block 435, functionality 400 may include receiving, by thesecond radio of the first network device, an association request. Theassociation request may be based on (e.g., in response to) anauthentication response. In some examples, the association request maybe received from the second network device. In addition, the associationrequest may be received from the second radio of the second networkdevice. The association request may be received in a particular sectorreceiving direction of the first network device. The particular sectorreceiving direction of the first network device may correspond to aparticular sector transmitting direction of the first network device. Inaddition, the sector transmitting direction of the first network devicemay correspond to a particular sector transmitting direction indicatedby the probe request. In some examples, the association request may bereceived in a particular beam receiving direction of the first networkdevice corresponding to a particular sector transmitting direction ofthe first network device.

As shown in block 440, functionality 400 may include transmitting, bythe second radio of the first network device, an association response ina particular sector transmitting direction. The association response maybe transmitted based on (e.g., in response to) associating the secondradio of the second network device. In some examples, the associationresponse may establish a connection between the first network device andthe second network device. The association response may be transmittedin a sector transmitting direction corresponding to a particular sectortransmitting direction indicated by the probe request. In some examples,the association response may be transmitted in a particular beamtransmitting direction corresponding to a particular sector transmittingdirection of the first network device.

As shown in block 445, functionality 400 may include transmitting, bythe second radio of the first network device, a data frame to the secondnetwork device in a particular sector transmitting direction. The dataframe may be transmitted to the second network device based on (e.g., inresponse to) an established connection between the first network deviceand the second network device. In some examples, the data frame may betransmitted to the second radio of the second network device. The dataframe may be transmitted in a sector transmitting directioncorresponding to a particular sector transmitting direction indicated bythe probe request. In some examples, the data frame may be transmittedin a particular beam transmitting direction corresponding to aparticular sector transmitting direction of the first network device.

As shown in block 450, functionality 400 may include receiving, by thesecond radio of the first network device, a data frame from the secondnetwork device. The data frame may be received from the second networkdevice based on (e.g., in response to) an established connection betweenthe first network device and the second network device. In someexamples, the data frame may be received from the second radio of thesecond network device. The data frame may be received in a particularsector receiving direction of the first network device. In addition, theparticular sector receiving direction may correspond to a particularsector transmitting direction indicated by the probe request. In someexamples, the data frame may be received in a particular beam receivingdirection of the first network device corresponding to the particularsector receiving direction.

In this manner, functionality 400 of FIG. 4 may provide multi-banddirectional scanning. For instance, functionality 400 may include,receiving, by a first radio of a first network device operating a firstfrequency band below the mmWave, a probe request (at block 405), andtransmitting, by a second radio of the first network device operating ata second frequency band within the mmWave, a probe response in eachsector transmitting direction (at block 415), based on determining thatthe probe request does not indicate a particular sector transmittingdirection (at block 410.) Thus, functionality 400 avoids requiringtransmitting, by the first network device via a frequency band withinthe mmWave, a beacon frame for every sector scanning direction of thesecond network device. Moreover, functionality 400 allows transmitting,by the second radio of the first network device operating at the secondfrequency band, the probe response in each of one or more sectordirections, wherein the second network device receives one or more proberesponses in the particular sector scanning direction, thereby allowingone or more probe responses to be received by the second network devicein the particular sector scanning direction, rather than requiring oneor more probe responses to be received in every sector scanningdirection of the second network device. Thus, examples described hereinmay provide may reduce scan times as compared to passive directionalscanning.

Moreover, functionality 400 may include receiving, by a first radio of afirst network device operating a first frequency band below the mmWave,a probe request (at block 405), and transmitting, by a second radio ofthe first network device operating at a second frequency band within themmWave, a probe response in a particular sector transmitting direction(at block 420), based on determining that the probe request indicatesthe particular sector transmitting direction (at block 410). Thus,functionality 400 allows transmitting, by the second radio of the firstnetwork device, the probe response in the particular sector transmittingdirection, rather than requiring transmitting the probe response inevery sector transmitting direction of the second network device.

FIG. 5 is a block diagram of an example computer system 500 in whichvarious embodiments described herein may be implemented.

Computer system 500 includes bus 505 or other communication mechanismfor communicating information, at least one hardware processor 510coupled with bus 505 for processing information. At least one hardwareprocessor 510 may be, for example, at least one general purposemicroprocessor.

Computer system 500 also includes main memory 515, such as random accessmemory (RAM), cache, other dynamic storage devices, or the like, or acombination thereof, coupled to bus 505 for storing information and oneor more instructions to be executed by at least one processor 510. Mainmemory 515 also may be used for storing temporary variables or otherintermediate information during execution of one or more instructions tobe executed by at least one processor 510. Such one or moreinstructions, when stored on storage media accessible to at least oneprocessor 510, render computer system 500 into a special-purpose machinethat is customized to perform the operations specified in the one ormore instructions.

Computer system 500 may further include read only memory (ROM) 520 orother static storage device coupled to bus 505 for storing static of oneor more instructions to be executed by at least one processor 510. Suchone or more instructions, when stored on storage media accessible to atleast one processor 510, render computer system 500 into aspecial-purpose machine that is customized to perform the operationsspecified in the one or more instructions.

Computer system 500 may further include information and one or moreinstructions for at least one processor 510. At least one storage device525, such as a magnetic disk, optical disk, or USB thumb drive (Flashdrive), or the like, or a combination thereof, may be provided andcoupled to bus 505 for storing information and one or more instructions.

Computer system 500 may further include display 530 coupled to bus 505for displaying a graphical output to a user. The computer system 500 mayfurther include input device 535, such as a keyboard, camera,microphone, or the like, or a combination thereof, coupled to bus 505for providing an input from a user. Computer system 500 may furtherinclude cursor control 540, such as a mouse, pointer, stylus, or thelike, or a combination thereof, coupled to bus 505 for providing aninput from a user.

Computer system 500 may further includes at least one network interface545, such as a network interface controller (NIC), network adapter, orthe like, or a combination thereof, coupled to bus 505 for connectingcomputer system 500 to at least one network.

In general, the word “component,” “system,” “database,” and the like, asused herein, can refer to logic embodied in hardware or firmware, or toa collection of software instructions, possibly having entry and exitpoints, written in a programming language, such as, for example, Java, Cor C++. A software component may be compiled and linked into anexecutable program, installed in a dynamic link library, or may bewritten in an interpreted programming language such as, for example,BASIC, Perl, or Python. It will be appreciated that software componentsmay be callable from other components or from themselves, and/or may beinvoked based on (e.g., in response to) detected events or interrupts.Software components configured for execution on computing devices may beprovided on a computer readable medium, such as a compact disc, digitalvideo disc, flash drive, magnetic disc, or any other tangible medium, oras a digital download (and may be originally stored on a compressed orinstallable format that requires installation, decompression ordecryption prior to execution.) Such software code may be stored,partially or fully, on a memory device of the executing computingdevice, for execution by the computing device. Software instructions maybe embedded in firmware, such as an EPROM. It will be furtherappreciated that hardware components may be comprised of connected logicunits, such as gates and flip-flops, and/or may be comprised ofprogrammable units, such as programmable gate arrays or processors.

Computer system 500 may implement the techniques described herein usingcustomized hard-wired logic, one or more ASICs or FPGAs, firmware and/orprogram logic which in combination with the computer system causes orprograms computer system 500 to be a special-purpose machine. Accordingto one embodiment, the techniques herein are performed by computersystem 500 based on (e.g., in response to) at least one processor 510executing one or more sequences of one or more instructions contained inmain memory 515. Such one or more instructions may be read into mainmemory 515 from another storage medium, such as at least one storagedevice 525. Execution of the sequences of one or more instructionscontained in main memory 515 causes at least one processor 510 toperform the process steps described herein. In alternative embodiments,hard-wired circuitry may be used in place of or in combination withsoftware instructions.

In examples described herein, the term “Wi-Fi” is meant to encompass anytype of wireless communications that conforms to any IEEE 802.11standards, whether 802.11ac, 802.11ad, 802.11ay, 802.11ax, 802.11g, etc.The term “Wi-Fi” is currently promulgated by the Wi-Fi Alliance®. Anyproducts tested and approved as “Wi-Fi Certified” (a registeredtrademark) by the Wi-Fi Alliance® are certified as interoperable witheach other, even if they are from different manufacturers. A user with a“Wi-Fi Certified” (a registered trademark) product can use any brand ofWAP with any other brand of client hardware that also is certified.Typically, however, any Wi-Fi product using the same radio frequencyband (e.g., 5 GHz band for 802.11ac) will work with any other, even ifsuch products are not “Wi-Fi Certified.” The term “Wi-Fi” is furtherintended to encompass future versions and/or variations on the foregoingcommunication standards. Each of the foregoing standards is herebyincorporated by reference.

In examples described herein, “throughput” refers to a rate ofsuccessful data transmission across a communication link. Throughput maydepend on a bandwidth of the communication link, a maximum rate of datatransmission (i.e., peak data rate or peak bit rate) across thecommunication link, or a combination thereof. Moreover, throughput maydepend on an amount of data packet loss during data transmission acrossthe communication link. For example, a network device may increasethroughput, and thereby improve performance, by increasing bandwidth ofa communication link, reducing data packet loss during data transmissionacross the communication link, or a combination thereof.

In examples described herein, “beamwidth” refers to an area for which atransmitted signal has a certain level of power. In some examples,beamwidth is expressed as an angle between two points of a transmittedsignal along an azimuth plane, wherein the transmitted signal has acertain level of power within that angle. In some examples, beamwidthmay correspond to the half power beamwidth of a transmitted signal. Asused herein, half power beamwidth corresponds to the angle between twopoints of a transmitted signal along an azimuth plane wherein the powerof the transmitted signal maintains a power of at least 50% (−3 dB) fromthe point of maximum radiation.

In examples described herein, the term “non-transitory media,” andsimilar terms, refers to any electronic, magnetic, optical, or otherphysical storage device that contains or stores executable instructions.Non-transitory media may comprise non-volatile media and/or volatilemedia. Non-volatile media includes, for example, optical or magneticdisks. Volatile media includes, for example, dynamic memory. Commonforms of non-transitory machine-readable media include, for example, afloppy disk, a flexible disk, hard disk, solid state drive, magnetictape, or any other magnetic data storage medium, a CD-ROM, any otheroptical data storage medium, any physical medium with patterns of holes,a RAM, a PROM, and EPROM, a FLASH-EPROM, NVRAM, any other memory chip orcartridge, and networked versions of the same.

Non-transitory media is distinct from but may be used in conjunctionwith transmission media. Transmission media participates in transferringinformation between non-transitory media. For example, transmissionmedia includes coaxial cables, copper wire and fiber optics.Transmission media can also take the form of acoustic or light waves,such as those generated during radio-wave and infra-red datacommunications.

As used herein, the term “or” may be construed in either an inclusive orexclusive sense. Moreover, the description of resources, operations, orstructures in the singular shall not be read to exclude the plural.Conditional language, such as, among others, “can,” “could,” “might,” or“may,” unless specifically stated otherwise, or otherwise understoodwithin the context as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements and/or steps.

Terms and phrases used in this document, and variations thereof, unlessotherwise expressly stated, should be construed as open ended as opposedto limiting. As examples of the foregoing, the term “including” shouldbe read as meaning “including, without limitation” or the like. The term“example” is used to provide exemplary instances of the item indiscussion, not an exhaustive or limiting list thereof. The terms “a” or“an” should be read as meaning “at least one,” “one or more” or thelike. The presence of broadening words and phrases such as “one ormore,” “at least,” “but not limited to” or other like phrases in someinstances shall not be read to mean that the narrower case is intendedor required in instances where such broadening phrases may be absent.

While the present techniques may be susceptible to various modificationsand alternative forms, the examples discussed above have been shown onlyby way of example. It is to be understood that the techniques are notintended to be limited to the particular examples disclosed herein.Indeed, the present techniques include all alternatives, modifications,and equivalents falling within the true spirit and scope of the appendedclaims.

The invention claimed is:
 1. A first network device, comprising: a firstradio operating at a first frequency band below a millimeter-wave(mmWave); a second radio operating at a second frequency band within themmWave; a first processing resource; and a first machine-readablestorage medium comprising instructions executable by the firstprocessing resource to: receive, by the first radio, a probe requestfrom a second network device indicating a protocol and a particularsector scanning direction of the second network device; receive, by thesecond radio, an association request from the second network device; andin response to the protocol indicated by the probe request, transmit, bythe second radio, a probe response in each of one or more sectortransmitting directions and an association response to the secondnetwork device, wherein the second network device receives one or moreprobe responses in the particular sector scanning direction.
 2. Thefirst network device of claim 1, wherein the processing resource isfurther configured to: receive, by the second radio, an authenticationrequest from the second network device, wherein the authenticationrequest is in response to the one or more probe responses received bythe second network device in the particular sector scanning direction;and in response to the authentication request, transmit, by the secondradio, an authentication response to the second network device.
 3. Thefirst network device of claim 1, wherein the association request is inresponse to the one or more probe responses received by the secondnetwork device in the particular sector scanning direction, and whereinthe association response establishes a connection with the secondnetwork device.
 4. The first network device of claim 3, wherein theprocessing resource is further configured to: based on an establishedconnection with the second network device, transmit, by the secondradio, a data frame to the second network device.
 5. The first networkdevice of claim 3, wherein the processing resource is further configuredto: based on an established connection with the second network device,receive, by the second radio, a data frame from the second networkdevice.
 6. The first network device of claim 1, wherein the proberequest indicates a particular scanning channel of the second networkdevice, a particular scanning duration of the second network device, ora combination thereof.
 7. The first network device of claim 1, whereinthe sector scanning direction of the second network device correspondsto a plurality of beam scanning directions of the second network device.8. The first network device of claim 1, wherein each of the one or moresector transmitting directions corresponds to a plurality of beamtransmitting directions.
 9. The first network device of claim 1, whereinthe first frequency band comprises a 5 GHz band.
 10. The first networkdevice of claim 1, wherein the second frequency band comprises a 60 GHzband.
 11. The first network device of claim 1, wherein the second radiocomprises a phased array antenna.
 12. The first network device of claim1, wherein the probe request indicates a particular transmittingdirection of one or more sector transmitting directions.
 13. A system,comprising: the first network device of claim 1; and the second networkdevice, comprising: a third radio operating at the first frequency band;a fourth radio operating at the second frequency band; a secondprocessing resource; and a second machine-readable storage mediumcomprising instructions executable by the second processing resource to:transmit, by the third radio, the probe request; receive, by the fourthradio, the one or more probe responses in the particular sector scanningdirection.
 14. A method, comprising: receiving, by a first radio of afirst network device operating at a first frequency band below amillimeter-wave (mmWave), a probe request from a second network deviceindicating a protocol and a particular sector scanning direction of thesecond network device; receiving, by a second radio of the first networkdevice, an association request from the second network device; inresponse to the protocol indicated by the probe request, transmitting,by a second radio of the first network device operating at a secondfrequency band within the mmWave, a probe response in each of one ormore sector transmitting directions and an association response to thesecond network device, wherein the second network device receives one ormore probe responses in the particular sector scanning direction. 15.The method of claim 14, further comprising: receiving, by the secondradio of the first network device, an authentication request, whereinthe authentication request is in response to the one or more proberesponses received by the second network device in the particular sectorscanning direction; and in response to the authentication request,transmitting, by the second radio of the first network device, anauthentication response in a particular sector transmitting direction.16. The method of claim 14, wherein the association request is inresponse to the one or more probe responses received by the secondnetwork device in a particular sector scanning direction, and whereinthe association response is transmitted in a particular sectortransmitting direction.
 17. The method of claim 16, further comprising:based on an established connection between the first and second networkdevices, transmitting, by the second radio of the first network device,a data frame in a particular sector transmitting direction.
 18. Themethod of claim 16, further comprising: determining the particularsector transmitting direction based on a determination of a quality ofthe one or more probe responses received by the second network device inthe particular sector scanning direction.
 19. The method of claim 16,wherein the particular sector scanning direction of the second networkdevice corresponds to a plurality of beam scanning directions of thesecond network device.
 20. An article comprising at least onenon-transitory machine-readable storage medium comprising instructionsexecutable by the at least one processing resource of a first networkdevice to: receive, by a first radio of the first network deviceoperating at a first frequency band below a millimeter-wave (mmWave), aprobe request from a second network device indicating a protocol and aparticular sector scanning direction of the second network device;receive, by a second radio of the first network device, an associationrequest from the second network device; in response to the protocolindicated by the probe request, transmit, by a second radio of the firstnetwork device operating at a second frequency band within the mmWave, aprobe response in each of one or more sector transmitting directions andan association response to the second network device, wherein the secondnetwork device receives one or more probe responses in the particularsector scanning direction.